and its relation to that in the Animal Kingdom. 259 



tures, the development of which into new individuals had not 

 yet been observed. 



They ordinarily occur upon distinct individuals, and occupy 

 upon thera the same places as the fruits on the fertile plants. 

 Their essential portion consists of numerous small round cel- 

 lules, which are sometimes grouped, without any envelope, upon 

 special organs, or definite regions of the frond, but sometimes 

 enclosed by a common cuticle. These cellules were com- 

 pared by Nageli* with the spermatic cellules of the antheridia 

 of Mosses, and he believed that he detected in them a spiral 

 filament lying upon the wall. Derbes and Solierf also believe 

 that each cellule contains an antherozoid, with a filiform append- 

 age as an organ of motion. 



ThuretJ demonstrated with certainty the absence of this 

 structure. According to him each antheridial cellule contains a 

 hyaline, spherical or longish corpuscle, with somewhat granular 

 contents {antherozoid) j which is expelled with a slow movement 

 from the cell, but then comes to perfect rest. Mettenius§ could 

 detect no movement of these corpuscles, which he regarded as 

 cells formed out of the entire contents of the antheridial cells. 

 He applied to them the name of ^seminal cellules' [Samenzellchen) 

 but declared himself inclined to regard them as spores which do 

 not possess the power of germination. Pringsheim||, who calls 

 them simply antheridium- cells, compares the statements of 

 Thuret and Mettenius ; the absence of movement is insufficient, 

 in the face of the agreement of their structure with that of the 

 spermatozoids of Fucacese and of Sphacelariaj to permit his as- 

 serting them not to be the real spermatozoids of the Floridese. 



At the same time, this author concludes, from his observations 

 on the germination of the tetraspores and capsule-spores of 

 Ceramium, that the former, which produce immediately a new 

 plant resembling the parent, only officiate like buds, for asexual 

 propagation ; but that the capsule-spores are either themselves 

 the true female sexual organs of the Floridese (in those namely 

 where the capsule-fruit has a canal penetrating into its interior), 

 or (in those with a closed fruit, as Ceramium) that the structure 

 produced from them in germination, unlike in appearance to 

 the parent-frond, represents a kind of prothallium, which in 

 some manner takes on the female sexual function. 



* Nageli, Neuer. Algensystem. Zurich, 1847, p. 190. pi. 6 & 7; also in 

 Zeitschr. f. wiss. Bot. 3 & 4 Heft, p. 224 (Zurich, 1846), and Botan. Zeit. 

 1849, p. 569. 



t Derbes et Solier, Org. reprod. des Algues. Ann. des Sc. nat. 3 ser. 

 xiv. p. 275 et seq. (1851). 



X Rech. sur les Antherid. &c. Ann. des Sc. nat. 3 ser. xvi. p. 14 (1851). 



% Beitr. zur Botanik, pp. 36, 39, 42. 



II Ueb. Befmcht. der Alg. p. 16. 



17* 



